How to remove "grout" around top of tub

A friend has a Jacuzzi tub with plastic insert "walls". The was mildew on the grout which she attempted to hide with some sort of quick-fix grout. The mildew now looks terrible and I want to get rid of it all and redo it. What can I use to clean it out but not hurt the tub? A sharp chisel might work. Are there solvents or cleaning chemicals? Dremel tool? Wire brush???
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the plastic panel gaps were filled with grout or caulk?
bill
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There are grout removal tools. Go to the tile section of HD or Lowes. Dremel also makes a grout removal attachment.
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